Modern vehicles, particularly automobiles, mostly so-called SUVs are provided with external view cameras to enhance the driver's vision and to improve safety. Moreover, these cars are often equipped with sensors which detect approaching and passing cars from behind which are not visible to the driver in the rear mirrors due to the blind angle, and are not covered by the rear view mirrors.
In the prior art, rear view cameras are often integrated into the rear bumper or into the tail gate or the boot lid of the vehicle nearby the licence plate. Due to that position at the car body, camera lenses or protective lens covers or the sensors are exposed to the vehicle's surroundings and dirt and debris, mud, salt spray etc. accumulate on the lens or on a lens cover or on a sensor cover during operation of the vehicle. Particularly, if cameras and/or sensors are integrated in the rear bumper or in the tail gate of the vehicle, they are particularly exposed to dirt and mud spray.
Therefore, it is generally known to provide external washing systems for cleaning lenses and sensors.
Various cleaning concepts have been proposed in the art, either in order to prevent built-up of dirt and debris on the camera lens, or to achieve an enhanced cleaning result.
Normally, cleaning fluid nozzles and nozzle assemblies are mounted on a vehicle adjacent to a camera or to a sensor, and are positioned such that liquid from the nozzles may directly sprayed onto the surface to be cleaned. As already mentioned in the very beginning, the surface to be cleaned might be a lens cover, a lens dome or a sensor surface.
Generally, an issue with such systems is that the external viewing angle of the sensor or of the vision device should be as wide as even possible. For example, modern wide angle rear view systems advantageously cover at least a part of the rear bumper such that a parking distance indication may be easily provided to the driver. The demand for such wide angle lens systems and for nozzles being placed very close to the lens or lens cover is to some extent conflicting as with rear view cameras it might happen that the nozzles are also covered by the viewing angle of the sensor unit. If a visible image is to be displayed on a screen within the passenger compartment, the nozzles might be optically distracting.
Yet another drawback of a non-concealed arrangement of nozzles very close to the sensor is that such arrangement is also aesthetically not very pleasing.
Yet another issue with known cleaning systems is that cleaning systems for cameras or sensors are provided in addition to cleaning systems for headlamp cleaning and windshield cleaning so that the cleaning liquid consumption is an issue. In modern vehicles the space available for cleaning fluid tanks is rather restricted which is generally not compatible with the demand for additional cleaning systems for cameras, sensors etc.
A known vehicle-mounted camera cleaning device which addresses the need to reduce the cleaning fluid consumption is for instance disclosed in WO 2014/010580 A1. This vehicle-mounted camera cleaning device includes a nozzle carrier in which an air channel and a cleaning fluid channel converge. The cleaning fluid with the aid of the compressed air is turned into a cleaning fluid mist, and thus, the cleaning fluid consumption is reduced.
Various other attempts to reduce the cleaning fluid consumption have been made, for example by fine tuning the spraying characteristics of the nozzles.